Allawi's resignation is the first by a cabinet minister since Iraq's national unity government was formed in December 2010, and comes just months after opponents of Maliki attempted to oust him via a no-confidence motion.

“I resigned because Maliki refused to...(stop) political interference in my ministry,” Allawi said by telephone from London, referring to demands he made in late July for an end to meddling in his ministry.

He specifically pointed to attempts to control who could appoint and transfer senior officials, alleging that the prime minister asked that a number of director-generals in the communications ministry be transferred to different ministries against Allawi's wishes.

“Some of our DGs who are very truthful, they are working very hard, he (Maliki) asked me to transfer them back to their previous ministries,” Allawi said.

“I asked to keep them but he refused.”

His resignation is the first of Iraq's national unity government. Last year, electricity minister Raad Shallal al-Ani was fired for signing off on $1.7 billion in allegedly improper contracts.

Allawi is a member of the mostly Sunni-backed Iraqiya bloc that attempted earlier this year to withdraw confidence from Maliki's government.

“I required certain conditions from the prime minister, to stop the political interference in my ministry,” Allawi told AFP.

“Otherwise, I told him I am not ready to work at the ministry with this big interference.”

"I told him, either you fulfill those conditions or accept my resignation. He decided after one month to accept my resignation.”Allawi said he made the demands to Maliki on July 28.